The purpose of this study was to investigate the effects of a floor heating (condition F) and an air conditioning system (condition A) on thermal responses in the elderly in a purpose-built experimental house. Subjects were nine elderly men and nine university students. The air temperature at sitting head height in condition A was set at 27℃, and the maximum difference in vertical air temperature was 5℃. The air and floor temperatures in condition F were 23 and 29℃, respectively. There was no significant difference in thermal responses under the conditions A and F between elderly and young subjects. However, instep and sole skin temperatures related significantly to thermal comfort in elderly subjects, whereas the relationship was not found in young subjects.